As set forth in 1980 in John J. Osborn's U.S. Pat. 4,197,858, entitled Sensing Liquid Trap for Respiratory Gas Analyzing Systems, he said, although reliable and rapid response carbon dioxide gas meters for respiratory measurements have been developed for more than twenty-five years, such meters have not been widely used for respiratory monitoring. Yet the continuous measurement of respiratory CO.sub.2 concentration is very useful in the care of critical patients undergoing anesthesia, or on mechanical respirators. He further said the non use was based on the impracticability of any moisture or water traps in their collecting of water, before the water or moisture could reach the CO.sub.2 gas analyzer, on a continuous basis and without degrading the signal capabilities of the CO.sub.2 gas analyzer. He then illustrated and described his sensing, liquid trap made of plastic in an upright hollow cylindrical shape in which the patient's breaths enter downwardly, and after a flow directional change, to eliminate water, the drier breaths flow upwardly, enroute, via a shutoff valve, to the CO.sub.2 gas analyzer. When Mr. Osborn's liquid trap, using the fluidic separation process, fills with water, a sensing circuit operates to shut off the valve, thereby protecting the CO.sub.2 gas analyzer.
Mr. Richard A. Cronenberg, in 1982, in his U.S. Dept. No. 4,327,718, entitled, Continuously draining Trap for Removal of Condensate From a Patient Breathing Circuit, illustrates how his trap and a trap, like Mr. Osborne's, are positioned between a patient and their respective breathing apparatus.
As indicated by the disclosures of the water traps of Messrs. Osborn and Cronenberg, there remained a need for a very effective small water trap to be closely secured adjacent a respiration monitor, with both being very resistant to damage, when used together in critical areas of hospitals and for portable applications in harsh environments as found by paramedics, and during their use the excellent monitoring of the respiration of a critical patient would be successfully undertaken.